TACKLING THE COMPLEXITY IN THE MIDDLE OF THE PLATFORM

1. TACKLING THE COMPLEXITY IN THE MIDDLE OF THE PLATFORM Jovan Vidic Engineering Lead @ Zalando SE 16-05-2019

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3. ZALANDO IN NUMBERS > 5.4 billion EUR > 250 million 2018 3 visits per month > 300,000 > 15,000 > 79% employees in Europe of visits via mobile devices > 26 product choices million ~ 2,000 17 brands countries active customers

4. WE ARE CONSTANTLY INNOVATING TECHNOLOGY help our brand to HOME-BREWED, CUTTING-EDGE & SCALABLE WIN ONLINE technology solutions ~ 1,900 employees from 77 nations 7 4 tech locations (HQs in Berlin)

5. > 200 development teams > 1200 developers 5 Platform

6. CHECKOUT FLOW CART 6 LOGIN ADDRESS PAYMENTS CONFIRM SUCCESS

7. Where’s the complexity? 7

8. Scalability

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12. Reliability

13. What’s absolutely needed to enter checkout? 13

14. Retry 14

15. 15 https://aws.amazon.com/blogs/architecture/exponential-backoff-and-jitter/

16. Open Circuit 16 Fallback

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20. Make a decision 20

21. SLOs It’s impossible to manage a service correctly, let alone well, without understanding which behaviors really matter for that service and how to measure and evaluate those behaviors. To this end, we would like to define and deliver a given level of service to our users, whether they use an internal API or a public product. - Google SRE Book 21

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23. Post Mortem 23

24. Domain modeling

25. How would you model shopping cart? 25

26. Using tactical DDD to design microservices 26 https://docs.microsoft.com/bs-latn-ba/azure/architecture/microservices/images/ddd-patterns.png

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29. Article sellable

30. What is shopping cart? 30

31. Hexagonal architecture 31

32. Delivery

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35. Correlation vs Causation 35 https://i.kinja-img.com/gawker-media/image/upload/18calq4ybym0sjpg.jpg

36. Flow 36

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40. WE PUT CUSTOMER SATISFACTION FIRST 40

41. Thank you

42. QUESTIONS? Don't miss talks from my colleague Luis Mineiro “Alerting, Monitoring and All that Jazz” "Are we all on the same page? Let's fix that" We're Hiring! https://jobs.zalando.com